Seminar: Let us take the opportunity to play Hide and Seek: where and what is the magnetic order?

Abstract: In this presentation we will concentrate on magnetic systems with heavy atoms, which means that the spin orbit coupling is significant. This strong coupling leads to that the spin and orbital degrees of freedom of the valence electrons are strongly mixed and intertwined which require a careful treatment where these degrees are handled on equal footing. Such a method [1] is conceptually introduced and its implications is discussed. In this context we will put some effort to discuss and seek the possibility that the formation of complex magnetic order may be not observable, which is often referred to as hidden order [2]. Lastly we will also discuss the fact that systems that are candidates for hidden order often displays an instability to unconventional superconductivity at low temperature. We will focus on the example of a newly discovered superconductor which is attracting large interests and showing several striking properties, UTe [2,3].

References:

[1] Bultmark et al, Phys Rev B 80, 035121 (2009); Cricchio et al, Euro Phys Lett 94, 57009 (2011)

[2] Cricchio et al, Phys Rev Lett 103, 107202 (2009)

[3] Ran et al, Science 365, 684 (2019)